Analog-to-digital converters (ADCs) convert time-discrete analog input values to a digital form. A type of ADC, the Σ-Δ modulator, digitizes the analog input values, and then analogizes the digital output signal by means of a digital-to-analog-converter (DAC), feeding the analog value back to at least a subsequent analog input value. Σ-Δ ADCs may be operated at a high frequency. A distribution of the quantization noise, which results from quantization errors, can be achieved by means of a larger spectral range. The quantization noise can then be better eliminated from the digital output signal with the aid of suitable filters, for example.
One form of noise shaping, in the case of Σ-Δ modulators, includes shaping the quantization noise by feeding back the digital output signal of the quantizer (in analog form) to an earlier stage of the ADC. For example, the feedback may return the analog output to the ADC input.